#robotics Logs
Feb 19 2017
#robotics Calendar
12:50 AM rue_shop3: im starting to run into an inability to find old thing designs on my server
01:07 AM Snert: sounds like a mouseular malfunction, or perhaps a cognitive indexing delineation misappropriation.
01:07 AM Snert: commonly known as "can't find squat".
01:09 AM Snert: I got so many usb sticks I can't find anything either.
01:17 AM z64555: This is why indexing systems exist
01:17 AM * z64555 hides
01:19 AM Snert: but a cognitive indexing delineation malfunction can defeat the initial assumption of data validity.
01:20 AM Snert: "it ain't fucking there".
01:24 AM z64555: yes, I'm a victim of that
01:53 AM rue_shop3: hmm, the motor cuased a surge that made the 78L05 fail and push 9V to the avr
01:53 AM rue_shop3: I wonder if its ok
01:53 AM rue_shop3: not having success with the chineese 78L05 chips, they been failing like crazy
01:53 AM z64555: o_o
01:54 AM rue_shop3: I think they are only good as non-current providing voltage references
01:55 AM Jak_o_Shadows: Literally 6 hours later, and i'ts mostly working
01:55 AM Jak_o_Shadows: except not qauite
01:57 AM rue_shop3: whats it again?
02:36 AM Jak_o_Shadows: LED bar graph display. For a pot. https://learn.sparkfun.com/tutorials/dotbar-display-driver-hookup-guide/example-hookup---cascading
02:36 AM Jak_o_Shadows: For my joystick project.
02:36 AM Jak_o_Shadows: I wanted the ability to have one big display, or two half displays, so I put a bunch of jumpers in.
02:43 AM rue_house: or just use an avr
02:43 AM rue_house: I love those chips, dont get me wrong
03:04 AM Jak_o_Shadows: Oh yeah, it is a damn cool chip.
03:04 AM Jak_o_Shadows: I didn't realise the amount of wiring required.
03:06 AM Jak_o_Shadows: I didn't really have a plan going in as to how I'id make it
03:06 AM Jak_o_Shadows: Also, I need to change out some resistors. It's not properly capturing the full range of the POT
03:07 AM Jak_o_Shadows: Then again, I did use the values from the datasheet example - which is for 8V +VE, and a signal of 4.46 -> 5.54V
03:09 AM Jak_o_Shadows: You'd have to use a fairly high pin count AVR though - or get it to cascade how? PWM a signal out?
04:18 AM z64555: multiplexer
04:18 AM * z64555 should sleep
04:21 AM z64555: uh, no, not a multiplexer
04:21 AM * z64555 slaps himself awake a bit
04:22 AM z64555: Yes, a multiplexer, but have it cycle through each led
04:23 AM z64555: You'd then have one pin for on/off and then n pins for up to 2^n leds
04:25 AM z64555: you might need a cap per led, though
04:26 AM z64555: I don't think you do, so long as the cycle frequency is high enough
04:26 AM z64555: besides, it'll look cool on camera
05:15 AM Jak_o_Shadows: oh, derp, or just like, multiplex or something
05:55 AM z64556 is now known as z64555
09:31 AM Tom_itx is now known as Tom_L
11:50 AM rue_shop3: cnc stopped again
12:07 PM z64555: If the bar led was just multiplexed, then only a single LED would be lit
01:22 PM rue_house: charlieplexing!
01:31 PM z64555: ?
01:33 PM z64555: huh. neat
01:33 PM z64555: https://en.wikipedia.org/wiki/Charlieplexing
01:42 PM rue_house: https://github.com/ruenahcmohr/charlieplex
03:45 PM justan0theruser: will most machine shops join timing belts for me?
03:45 PM justan0theruser: Or do I need to buy a kit?
03:45 PM rue_house: no you buy them the right size
03:46 PM justan0theruser: where
03:46 PM justan0theruser: oh sorry, you're a troll, disregard response
03:56 PM z64555: Timing belts aren't "joined" together. they're not leather
03:57 PM z64555: Timing chains are
03:57 PM z64555: s/are/are joined together because it's a metal chain
03:58 PM z64555: oh, that bot is on a different network
04:03 PM Tom_L: haha justan0theruser calling rue_house a troll...
04:03 PM synja: humourous
04:08 PM * rue_shop3 looks around
04:12 PM justan0theruser: Tom_L: he really is though, every time I've engaged him he's used it to troll
04:12 PM z64555: nah, that's just sarcasm
04:13 PM justan0theruser: z64555: https://www.mcmaster.com/#timing-belts/=16fd6l7
04:13 PM justan0theruser: z64555: is mcmaster using the wrong terminology? https://www.mcmaster.com/#62065K41
04:13 PM Tom_L: justan0theruser i tend to disagree with your observations
04:14 PM Tom_L: maybe he doesn't think you're worthy
04:14 PM justan0theruser: whatever, theres no point in justifying it, all I know is that he's wasted enough of my time to not engage him
04:15 PM justan0theruser: anyways, I want a urethane belt that is cut to be made into a ring
04:15 PM Tom_L: i would too if i noticed you lack ability or willingness
04:15 PM Tom_L: get one from sdp-si
04:16 PM Tom_L: you don't join belts
04:16 PM justan0theruser: is mcmaster using the wrong terminology then?
04:16 PM Tom_L: not timing belts
04:16 PM synja: then just ignore him. yes, he's self-centered, with resources in plenty, lashes out irrationally; but i've never seen him troll
04:16 PM z64555: no, you're just confused
04:16 PM Tom_L: ^^
04:16 PM justan0theruser: please explain
04:17 PM Tom_L: don't feel i need to
04:17 PM justan0theruser: not talking to you
04:17 PM z64555: "cut-to-length" belts are those specifically made to be able to be joined. The standard type of belts cannot be joined, and must be manufactored the correct length to begin with
04:18 PM z64555: hm, wait
04:19 PM justan0theruser: z64555: so you're saying that cut to length belts are able to be joined, timing belts cannot be joined, and cut to length belts can be timing belts
04:19 PM justan0theruser: this is not possible
04:19 PM z64555: stop being anal about semantics
04:19 PM z64555: it annoys everone
04:19 PM justan0theruser: ...
04:20 PM justan0theruser: It's not semantics, I do not know what you're telling me or which of these is true
04:21 PM ace4016: there are timing belts that are of a fixed sized, there are timing belts that you can cut and join to size, and there are timing chains
04:21 PM z64555: I was mistaken. "cut-to-length" belts are _not_ designed to be re-joined together
04:21 PM z64555: They're designed to be anchored to some other part
04:22 PM z64555: Like with a printer head, the ends are anchored to the head and the belt loops around an idler pulley and a servo pulley
04:23 PM justan0theruser: I am trying to transfer energy from one axle to another. If I am to use a timing belt, I cannot form a circle, I can only transfer energy on the bottom or top of both axles?
04:23 PM justan0theruser: Ah I see
04:24 PM z64555: the belt should hug around both axles, ideally half of the surface area of both contact circles is engaged
04:24 PM justan0theruser: so I will just have loose belt that I will try to keep out of the way of everything somehow?
04:24 PM z64555: use a tensioning pulley
04:25 PM z64555: if the contact circles is wide enough, you can put the tensioner outside of the belt and push it inward
04:25 PM z64555: this will give you both more tension on as well as more contact area
04:25 PM z64555: If the axles are close enough, you won't need an idler
04:26 PM z64555: sigh
04:26 PM z64555: no
04:26 PM z64555: not close enough
04:26 PM * z64555 is barely awake
04:27 PM justan0theruser: where should I look for a timing belt tensioning pulley, mcmaster doesn't seem to have them, I see this on ebay though
04:27 PM justan0theruser: http://www.ebay.com/itm/DAYCO-Auto-belt-tensioner-A-C-FOR-Iveco-Trakker-09-13L-Turbo-Diesel-337kW-Cursor/182428060149?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D41376%26meid%3D68aaab5e269b429299eada68c430cdd8%26pid%3D100005%26rk%3D1%26rkt%3D1%26sd%3D182428060081
04:28 PM Tom_L: make one
04:28 PM z64555: The tension on a timing belt does not need to be high, as long as the teeth of the pulleys engage it will work
04:29 PM z64555: a tensioning pulley is just a simple pulley that has some sort of spring mechanism to pull on the belt
04:30 PM z64555: Usually, it's a pulley at the end of a lever. with a spring on it. very simple to build
04:30 PM z64555: IIRC, we went over them before
04:31 PM z64555: and you insisted on buying one rather than trying to fabricate one
04:33 PM justan0theruser: z64555: What we were discussing previously was something that automatically tensioned a circular belt http://www.ebay.com/itm/141740214681
04:34 PM justan0theruser: that is what I ended up using
04:35 PM justan0theruser: seems something very similar could be made for an unconnected belt, however
04:39 PM z64555: yes, it works on the same princples
04:40 PM justan0theruser: not sure how I would design the base though, might be easier to buy a tensioning pulley then mount an at10 pulley to it
04:40 PM justan0theruser: the base being the part with the spring I mean
04:46 PM justan0theruser: oh I misunderstood, this is very easy, just mount the pulley and attach the spring to the belt
04:46 PM justan0theruser: or why not just use a spring without the pulley?
04:54 PM justan0theruser: Unless there is a flaw with that I'm gonna do that :)
05:05 PM justan0theruser: I don't see a problem with that, so I'm going to go ahead, thanks for your help!
05:46 PM justan0theruser: why don't they sell spiders rated for the same torque as the coupling hubs. Is the torque distributed between the three components relatively evenly?? https://www.mcmaster.com/#catalog/123/1237/=16feqhp
07:02 PM SpeedEvil: justan0theruser: Because the spider is not made from stainless steel
07:04 PM justan0theruser: SpeedEvil: but why even offer the other components if the spider can't handle the torque
07:04 PM justan0theruser: is the torque distributed evenly between the three components?
07:05 PM SpeedEvil: More seriously, I find one torque, not two, what do you mean
07:05 PM justan0theruser: one torque?
07:05 PM justan0theruser: there is the coupling hubs torque and the spiders torque
07:06 PM SpeedEvil: they list lines, with the hub and the spider on the same line.
07:06 PM SpeedEvil: Only the spider has a listed torque
07:07 PM justan0theruser: so that is where most of the torque is placed?
07:08 PM SpeedEvil: All of the torque is identicall on all components of a shaft
07:08 PM justan0theruser: I see, sorry I'm not familiar with the physics of this
07:09 PM SpeedEvil: (unless something adds or subtracts to it like an external gear
07:09 PM SpeedEvil: but the torque on the input, spider, and ouptu will be identical
07:20 PM rue_shop3: so I accidently jabbed the fan of my printer with a putty knife and broke off a blade
07:20 PM rue_shop3: AAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRGGGGGGGGGGGGG
07:20 PM synja: lol
07:21 PM synja: worse things have happened by accident, but that does stink
07:25 PM Tom_L: rue_shop3, break off the opposite blade to balance it
07:30 PM SpeedEvil: Or add weight to balance
07:30 PM synja: or print a piece to replace it
07:31 PM synja: using SpeedEvil's suggestion until then
07:33 PM synja: meh. printing an entire fan piece might not resonate well. superglue the piece back?
07:34 PM SpeedEvil: Suitable glue can work, if you can find a compatible one
07:34 PM SpeedEvil: The force on the blade is not that high unless some nutter jams it with a putty knife.
07:34 PM synja: lmao
07:44 PM rue_shop3: 5 blades
07:46 PM Tom_L: woops
07:48 PM z64555: yeah, that won't end well
11:07 PM rue_house: wtf, google moon dosn't have the whole moon
11:08 PM z64555: just the moon moon?
11:08 PM z64555: :3
11:08 PM rue_house: what a rip
11:08 PM rue_house: ditto mars
11:08 PM rue_house: its just a patch that repeats horizontally
11:11 PM rue_house: how the hell am I supposed to find 3455 1st street on Titan if google dosn't have an online map!
11:13 PM -!- #robotics mode set to +o by ChanServ
11:14 PM rue_house changed topic of #robotics to: If you ask a question, you must wait for the answer. | http://tom-itx.no-ip.biz:81/~webpage/index.php | G is for Gyroscope
11:14 PM -!- #robotics mode set to -o by rue_house
11:15 PM rue_house: or should I have gone to I
11:16 PM z64555: Io?
11:17 PM rue_house: how much inductance to go from 4A to 3.75A in 1/300 sec?
11:18 PM rue_house: I have about 1 hour left
11:18 PM rue_house: but I got a few things done this weekend
11:18 PM rue_house: mostly falling behind
11:23 PM z64555: I'm pretty boastful about an undo/redo system I made up recently
11:24 PM rue_house: I'v wondered a few times how to make one, but never sat down on it
11:24 PM z64555: https://github.com/scp-fs2open/fs2open.github.com/pull/1243
11:24 PM rue_house: do you cheat and just rewind time itself to before the users last operation?
11:24 PM z64555: If i could do that, I'd be sitting in someplace far more comfortable right now
11:25 PM z64555: No, I make use of C++'s template system to enforce type safety
11:25 PM z64555: and the concept of abstract classes and polymorphism
11:26 PM z64555: The underlying concept is pretty darn simple, Each saved item is a snapshot of the data before it's modified
11:26 PM z64555: the copy is stored on the heap, in C++ that uses operator new, and operator delete to manage
11:27 PM z64555: in C it would use malloc
11:27 PM z64555: and use void*'s
11:27 PM z64555: When it comes time to undo the operation, *dest = *data;
11:29 PM z64555: If you were forced to do it in C, you'd have to specialize for each struct type you're working with
11:29 PM z64555: but
11:29 PM z64555: If you're working with text
11:30 PM z64555: You don't have to worry so much about type safety, your data is all gonna be strings
11:30 PM rue_shop3: how big is the heap?
11:30 PM z64555: That's up to the std library and the archetecture that you're using
11:31 PM rue_shop3: rue_house, do the flashing led code for me
11:31 PM rue_shop3: so the heap might be small
11:31 PM rue_shop3: does it catch ok if the heap is out of space?
11:32 PM z64555: On a hardware level, the heap is whatever space on your stack that your OS isn't using
11:32 PM z64555: If the heap is out of space, malloc will fail
11:35 PM rue_shop3: aren't most stacks limited to 640k?
11:36 PM z64555: I don't have any numbers for the actual heap limits, sorry
11:45 PM z64555: Yeah, it's libarary/OS dependant. 32bit Windows, for example, allocates 2GB each program data and the heap
11:45 PM * z64555 I think